Some types of articles require a sequence of multiple metalworking steps and intermediate annealing steps during the manufacturing operation. For example, some gas turbine components are mechanically worked by rolling to the required configuration, thickness, and metallurgical structure from a starting workpiece. Specific gas turbine components manufactured in this manner include the airfoil portion of some types of wrought high-pressure compressor blades and vanes, and the rings used to produce the ring segments that form the inner and outer bands of segmented compressor vane structures. These components are made of nickel-base alloys selected to have the required mechanical performance at the operating temperature of the components.
The rolling from the starting workpiece to the required final configuration, thickness, and metallurgical structure cannot be accomplished in a single rolling operation because of metallurgical limitations. The workpiece work hardens during the rolling operation so that eventually its strength becomes too high and its ductility becomes too low for further rolling. At that point, it is solution annealed to soften the metal. The solution annealing temperature for the nickel-base alloys is usually about 1800–1900° F. in order to achieve the desired softening of the metal for available nickel-base alloys. The solution annealing is typically performed in a vacuum oven because the nickel-base alloys oxidize badly if annealed in air or even in commercial-quality nitrogen or inert gases at this required annealing temperature and for the times required to achieve the annealing.
After the solution annealing is complete, the annealed workpiece is further mechanically worked by additional rolling toward the required final configuration and thickness. The workpiece again work hardens, and may again require annealing before further rolling. Typically several sequences of rolling and solution annealing are required to achieve the desired final configuration.
This approach works well and has been used successfully for many years. However, there is a desire and a need to improve the economics by reducing the manufacturing costs. Any change in the manufacturing procedures must not cause a reduction in the quality of the finished articles. The present invention fulfills this need, and further provides related advantages.